This invention relates to cat litter boxes, and more particularly to a collapsible, portable, litter box made of a single piece construction which includes a fixed lower portion in which is fitted a disposable, mesh-type litter bag, and an expandable upper portion. The upper portion completely encloses the litter bag except for an opening for ingress and egress to the cat litter box. In the preferred embodiment, the mesh chosen is of a coarseness, such that when it is lifted out of the litter box, the litter is allowed to pass through, but the animal feces are not, and thus, the animal feces are removed.